|NELSON, ANDREW - University Of Illinois|
|KOLOUTSOU-VAKAKIS, SOTIRIA - University Of Illinois|
|ROOD, MARK - University Of Illinois|
|MYLES, LATOYA - National Oceanic & Atmospheric Administration (NOAA)|
|LEHMANN, CHRISTOPHER - Illinois State Water Survey|
|BALASUBRAMANIAN, SRINIDHI - University Of Illinois|
|JOO, EVA - University Of Illinois|
|HEUER, MARK - National Oceanic & Atmospheric Administration (NOAA)|
|VIEIRA-FILHO, MARCELO - Universidade Federal De Lavras|
Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2017
Publication Date: 5/28/2017
Citation: Nelson, A.J., Koloutsou-Vakakis, S., Rood, M., Myles, L., Lehmann, C., Bernacchi, C.J., Balasubramanian, S., Joo, E., Heuer, M., Vieira-Filho, M. 2017. Ammonia flux above fertilized corn in central Illinois, USA, using relaxed eddy accumulation. Agricultural and Forest Meteorology. 239:202-212.
Interpretive Summary: Ammonia is widely used as a fertilizer for crops but it can leave the soil through the atmosphere resulting in ammonia acting as a pollutant. Despite what is known about ammonia, there is very limited data that quantifies how much ammonia is released to the atmosphere after fertilizing crops. An experiment was undertaken to measure the rates of ammonia losses from a corn field in Central Illinois immediately after and for a period of time following fertilization. The results show a large research of ammonia right after fertilizer is applied, and this pulse out is much greater than the rate of ammonia falling on the soil during the winter. The results of this research help to understand the dynamics of ammonia losses after fertilization and can be used to better represent ammonia losses from crops through models that scale ammonia release or uptake over larger areas.
Technical Abstract: The objective of this research is to quantify NH3 flux above an intensively managed cornfield in the Midwestern United States to improve understanding of NH3 emissions and evaluations of new and existing emission models. A relaxed eddy accumulation (REA) system was deployed above a corn canopy in central Illinois, USA (40° 3’ 46.209” N, 88° 11’ 46.0212” W) from May 2014 through March 2015 to measure NH3 fluxes due to chemical fertilizer application. NH3 flux was measured in four-hour periods during mornings and afternoons. Mean atmospheric NH3 concentration during the complete measurement period was 2.6 ± 2.0 µg m-3. Larger upward fluxes of gaseous NH3 were measured during the first 30 days after fertilization, with variations observed throughout the field campaign. Measured NH3 fluxes ranged from -246.0 ng m-2 s-1 during wintertime background measurements to 799.6 ng m-2 s-1 within two weeks of fertilization (where negative flux indicates deposition). Mean positive flux was 233.3 ± 203.0 ng m-2 s-1 in the morning and 260.0 ± 253.3 ng m-2 s-1 in the afternoon while mean negative flux was -45.3 ± 38.6 ng m-2 s-1 in the morning and -78.35 ± 74.9 ng m-2 s-1 in the afternoon. Such measurements are critical to improve understanding of agricultural NH3 emissions in managed agricultural ecosystems dominated by rotations of highly fertilized corn and moderately to lightly fertilized soybeans, such as the plot studied herein. These measurements are also important to improve understanding of how managed agricultural ecosystems impact air quality, and contribute to the global nitrogen cycle, and to evaluate current NH3 emission models.